Ayaan Hirsi Ali is a woman who makes many European liberals very uncomfortable. A Somali, a Muslim, a woman and a refugee, she arrived in Holland, having fled an arranged marriage, and the severe limitations imposed on women by her clan, culture and religion. She took advantage of the generous Dutch social benefits and provisions, gained a degree, and, bizarrely enough, decided that secular liberal humanism was a wonderful thing.

A certain cast of guilty liberal would rather listen to Abu Hamza raving on about the corrupt and degenerate ways of the infidel than hear a black African woman say that west is best. But that's not the only reason why Hirsi Ali upsets people.

Not content with being an unapologetic proselytiser for Enlightenment values and the human rights and freedoms that stem from them, she is also a trenchant and outspoken critic of Islam. And therefore she has been accused of Islamophobia and even, by those who see Islam as a race rather than an ideology, a racist.

As a consequence of her stance on Islam she lived under round-the-clock police protection in Holland. Theo van Gogh, with whom she made a short film that featured Koranic verses that allow men to beat their wives, did not have such protection and he was shot dead and had his head half-cut off on the daytime streets of Amsterdam.

This perhaps is another reason why Hirsi Ali causes liberal unease. We don't like to be reminded of what can happen to those who dare to criticise the Prophet Muhammed. Certainly her neighbours in the Hague didn't like to be reminded, and they won a legal case ruling that Hirsi Ali's proximity placed them in jeopardy. She was evicted and she promptly moved to America.

So what are we to make of Hirsi Ali? Is she the "Enlightenment fundamentalist" of which the distinguished historians Tony Judt and Timothy Garton Ash both anxiously speak?

The answer I think is, yes, but not in the way that Judt and Garton and Ash mean. She is a fundamentalist insofar as she thinks that principles are not particularly helpful unless they are applied in practice. As we saw during the Danish cartoons crisis, the principle of free speech was one that the liberal intelligentsia in the media was all too willing to abandon.

There are many arguments on which it's perfectly reasonable to disagree with Hirsi Ali, but there are two crucial points on which only the illiberal can afford to dismiss what she has to say.

The first is her own experience as a Muslim woman growing up in the Third World and then arriving in Europe. In the first place, she was brought up to understand that women were the property of men, that Jews were the source of all the worlds problems, and that the answer to her predicament was to become a more faithful and observant Muslim.

In the second, she took control of her own destiny, and gained access to all the freedom and opportunity that European culture has to offer.

Many observers will look at the two situations and conclude that the overriding difference is economic. But Hirsi Ali insists that this is a misnomer that is leading us in the wrong direction. The reason that Saudi Arabian society, for example, has failed to develop secure rights and freedoms is not through shortage of money - nor, as some like to believe, because of the pernicious support of America. The problem is cultural, specifically the rigor mortis grip of Islam.

That, Hirsi Ali believes, is the same problem that faces many Muslims in the west. The alienation many feel is chiefly due not to racism but the difficulty of reconciling incompatible value systems. "That's what the integration debate is about," she says. "If you take those values with you and come here, it's not going to change your misery."

These may sound like insensitive words, but they lead us to Hirsi Ali's second major contribution. In her film Submission 1 and in a number of her writings, she has attempted to flush out some of the more controversial passages of the Koran. Hence her police protection. Hirsi Ali contends that there can be no proper debate about culture, customs or values until we can discuss and assess the Koran as we would any other text. Try as I might, I can see nothing to disagree with in that analysis.

As things stand, only the very brave and the foolish are willing to take on a religious system that maintains the oppression of millions of women across the globe. And say what you like about Hirsi Ali, she's no fool.